Visit Download.com to download iTunes Folder Watch for free. The unpaid version includes most of the main features offered by the app, but you'll be pestered by an annoying nag screen during startup and shut-down, as well as after tracks are added. Plus, forking over the one-time 7.50 Euro fee opens access to one particularly handy feature noted later on in this tutorial.
Once you have completed Step 2, click the "+" icon to add the folder to the monitoring list. Also, be sure to check the box under Include Subfolders if you want the program to add files from the main folder's subdirectories. Repeat steps 2 and 3 until all desired music folders are added. Then, click Check Now.
Click the New Tracks tab. Then, expand the folders to view the tracks inside. If desired, uncheck any songs you do not wish to be added to the library. (You may also click the Add Unchecked Files & Folders to Exclusions button if you never want the tracks added to your iTunes library.) Click Add Checked Tracks to iTunes.
If you wish to exclude tracks or subfolders from the process, click the Exclusions tab. Then, click the "+" to add desired exclusions. After you have adjusted all the settings to your liking, you can close the software. Each time you open it again, it will scan folders based on your preferences.
Downloading an app that you have to prompt each time you want to add new music is far from the most elegant solution, which is why we recommend paying to register iTunes Folder Watch. Once you do, you can set up the program to automatically add new files without you having to lift a finger and--after all--isn't that really the point?